1. Field of the Invention
The present invention relates to novel fumarate- and polyfumaramide-containing monomers and compositions comprising the monomers. Especially preferred are the polyfumarate- and polyfumaramide-containing compositions used to make highly oxygen permeable hydrogels which may be used to make biomedical devices including contact lenses.
2. Background
In the field of contact lenses, various factors must combine to yield a material that has appropriate characteristics. Polysiloxane materials are useful materials for making contact lenses due to, among other properties, their excellent oxygen permeability. See U.S. Pat. Nos. 4,153,641 and 4,189,546. However, certain polysiloxane materials are known to experience poor wetting.
Difunctional groups such as fumarates and maleates are known to be viable wetting comonomers in certain polysiloxane copolymeric systems. However, it is well known by those skilled in the field that fumarates often do not easily polymerize into high molecular weight polymers due to steric hindrance.
Certain bulky siloxane-containing fumarates, including bis(siloxanylalkyl)fumarate and (poly)alkylfluoroalkyl fumarates, reportedly may be used as copolymers to make hard contact lens materials. (See European Patent Application No. 86114829.4.) However, the known polymerization schemes for such fumarate-containing polymers, which are directed exclusively to hard contact lens materials, require a minimum of at least 24 hours of curing, and achieve only a low yield of the desired polymer.